"Japanese sword" refers to a sword with a blade on one side of the blade and a "warp", and has been used since the middle of the Heian period. Furthermore, it is also a condition of Japanese swords that they are made according to the ancient Japanese manufacturing method.
In addition, Japanese swords in a broad sense include "spear", "naginata" (naginata), and "sword" (ken / sword), and it cannot be excluded that the blade itself has artistic value.
The name Japanese sword is a general term for swords unique to Japan as seen from overseas. In Japan, it was called "serious" to distinguish it from "sword", sword, or wooden sword or bamboo sword.
The name "Japanese sword" appears in the "Japanese sword song" of the poet "Ouyang Xiu" of the Northern Song Dynasty (one of the old Chinese dynasties).